This invention relates to a workcentre and to supports therefor, and particularly to a wood-machining workcentre of the type comprising a frame mounting a router or like tool for movement in the frame in two, or more likely three orthogonal directions. Such movement may be under the control of a computer performing individual movements according to direct operator control or a sequence of movements according to pre-programmed control.
In any event, the frame comprises two (or three) linear elements each mounting a carriage slidable along the element under the action of a motor. In frames moving in three orthogonal directions, the first element is fixed with respect to a worktable; the second element is mounted perpendicularly with respect to the first element and is mounted on the carriage of the first element; and the third element is mounted perpendicularly to both the first and second elements on the carriage of the second element. A tool is mounted on the carriage of the third element.
The carriage is driven along the element by a motor and several options are available for connecting the motor to the carriage. For example, the motor may be mounted on the carriage and acting against the element. Alternatively, the motor may be mounted on the element and drive the carriage through a worm-drive screw or by a belt and pulleys on the carriage.
In any event, it is an object of the present invention to provide a workcentre whose construction is adaptable according to requirements.
In accordance with the present invention there is provided a workcentre comprising first, second and third linear elements each arranged in substantially orthoganol first, second and third directions respectively, the first element being fixed with respect to a worktable lying in a plane parallel to said first and second directions, the second element being fixed to a carriage of the first element, one end of said second element being supported against movement in said third direction, said third element being mounted on a carriage of said second element and a carriage of said third element carrying a tool for performing cutting operations on a workpiece supported on said worktable, said second element being adapted to be mounted on its carriage in one of two positions, in a first of which said carriage of the second element is between said one end and said carriage of the first element and in the second of which positions said carriage of the first element is between said one end and said carriage of the second element.
Said second element being supported against movement only in said third direction may include an end plate fixed at the end of the second element, said plate carrying bearing means, a rail being aligned parallel to said first element having tracks along which said bearing means are adapted to roll. Preferably said bearing means comprises three axles on each of which is journalled a bearing wheel.
Preferably all the axles are parallel and in the plane of said first and second directions, two tracks facing one another and lying parallel said plane, two end ones of said bearing wheels being adapted to roll on one track while the other central wheel is adapted to roll on the other track, each axle comprising an eccentric stub on which said wheel is mounted for adjustment in said third direction.
Alternatively said bearing means may comprise a single bearing wheel having a concave surface and said rail comprises a bar of corresponding mating shape with said concave surface.
Thus the workcentre according to the present invention is adaptable between two configurations. In a first configuration it is in overhang mode and the worktable is disposed between said first element and the rail so that workpieces no wider than the gap between the first element and rail can be machined by the workcentre. On the other hand, the second element is securely located at each end and therefore very accurate machining of the workpiece is possible.
In its second configuration, the workcentre is in its cantilever mode where the second element projects over the workpiece. The second element is mounted on the first element as close to said one end as possible, but not so close as to render the second element unstable given the length of it which is free. Neverthless, there is now no limit to the width of objects capable of being machined by the workcentre and the overall possible width of machining of an object can be larger than in its overhang mode if the second element is mounted on the carriage of the first element nearer said one end of the second carriage than its other end.
Moreover, while a router is a most suitable tool for machining operations in a workcentre according to the present invention, at least in its overhang mode, an alternative arrangement in said cantilever mode is the installation of a circular saw on the carriage of said third element to render the workcentre a radial arm saw.
Said adaptability of the workcentre is achieved by said elements each comprising an extruded support of substantially U-shaped section, the carriage being received within said support and mounted on bearing wheels journalled to said carriage and running on four tracks formed in said support, four of said bearing wheels being mounted at or adjacent each end of the carriage on axles received in said carriage, the support having a profile which includes keyhole slots for reception of self-tapping screws from the ends of the support and undercut slots for reception of bolt heads or nuts whose associated shank extends out of said slot for attachment of elements to the sides of said support.
In this manner, the second element can be attached to the carriage of the first element anywhere along the length of the second element simply by sliding bolt heads or nuts employed to secure the carriage and element together along said slots to the required position.
Thus it is preferred that said profile has a pair of said undercut slots opening in a direction opposite to the opening of the slot forming said U-shape.
Preferably two of said wheels at each end of the carriage are radially adjustable to take up free play between said carriage and support in a plane perpendicular to a carriage centre line, which line is parallel to said tracks.
Preferably said axles are substantially radial with respect to said centre line.
Preferably a plane passes through said line and divides said axles into pairs disposed symmetrically on either side of said plane.
Preferably said plane passes through the middle of a slot formed by said U-shaped section of the support and the respective tracks of each pair of axles are adjacent each other.
Preferably each track comprises a steel strip received in an undercut channel formed in said support.
Preferably the axles are adjustable by an eccentric stub section of the axle mounted in the wheel or support, said axle being rotatable in the support to adjust the angular position of said eccentric stub. Preferably only the axles remote from said slot are adjustable through holes formed in said support along its length for insertion of a tool to turn each axle.
Preferably the carriage is an extruded section having a main body mounting said axles and being received within said support and an integral carriage plate for attachment thereto of a second linear element or a tool.
An intermediate plate may be interposed between said second linear element and the carriage plate, said intermediate plate mounting further bearing wheels bearing against the outside of said U-shaped section support.
Preferably said axles each comprise a head, a haft concentric with said head and a stub on the end of said haft which is eccentric with respect thereto, said stub being threaded at its end to receive a nut and a bearing wheel being adapted for reception on said stub, the carriage comprising undercut channels into which said head is adapted to be received, said nut not only clamping said bearing wheel in position but also locking said axle in position.
The workcentre preferably further comprises a computer to control movement of said linear elements, each of which is driven by a motor.
Said second element may be mounted in the second of its two positions and said tool may be a circular saw. In this event, the motor of said third element may be arranged to rotate said saw about an axis parallel said third direction and said computer controls the angular position of the saw so that a blade of the saw is aligned withy the direction of movement of the saw, as controlled by the computer, in the plane of said first and second directions.
This enables mitre cuts to be effected by the saw. Moreover, means can be provided to ensure that movement is said first and second directions only occurs if the blade is first orientated in the direction of the resultant movement in the plane of said first and second direction.
The invention is further described hereinafter, by way of example only, with reference to the accompanying drawings.